In the preparation of a tooth or teeth for crowns, inlays, onlays, bridges and the like, dentists must eliminate undercuts from the tooth or teeth in question. It is undesirable to remove excessive tooth structure as would weaken the tooth or otherwise jeopardize its use as a supporting structure. With the advent of high speed drills, more tooth structure can be removed than is necessary in short order before realization of the fact.
By way of example, when a dentist prepares a patient's tooth to receive a crown or other restoration, ordinarily a high speed drill or the like is used to shape the tooth so that the non-occlusal surfaces converge toward the occlusal surface or path of insertion. If a portion of the tooth surface remains divergent, which is commonly referred to as an undercut, the metal crown will not conform to the tooth and a perfect fit cannot be otained. Hence elimination of undercut areas is necessary.
In the case of the preparation of a tooth for an inlay, ordinarily tooth structure is removed in a manner such that the resulting inner walls diverge toward the path of insertion thereby creating a recess in which the inlay may be placed. If any portion of the recess walls are convergent instead of divergent, an undercut is created which again prevents a perfect fit of an inlay to the tooth.
Heretofore, undercuts of the nature described have been removed by visually surveying the surface of a tooth and using a drill or other suitable means to remove tooth structure as necessary. As indicated previously, a shortcoming of this procedure is that excessive tooth structure can be removed before appreciation of the fact, and it would be highly advantageous to eliminate undercuts in a more precise manner so as to avoid excessive removal of tooth structure. The present invention is directed to a composition of matter and a method of use thereof that provides such advantageous results.